This invention relates to a gear pump of the type which is especially adapted to supply pressurized liquid fuel to an oil burner. The invention more particularly relates to a two-stage gear pump.
In such a gear pump, each stage comprises a pinion gear secured to a drive shaft and rotatable within a ring gear. It is conventional to couple the pinions to the shaft with keys which transmit the drive to the pinions.
Fuel pumps of the above type typically operate with low viscosity, low lubricity fuels. As a result of the low lubricity, prior two-stage gear pumps experience wear at the interfaces of the keys with the pinions and the drive shaft. Such wear eventually permits relative rotation between the pinions and the shaft and this leads to additional wear which reduces or destroys the effectivenss of the coupling between the pinions and the shaft.